The prior art includes automatic motor vehicle leveling systems, at least one of which requires only a single switch actuation to adjust to a level attitude an automotive vehicle such as a recreation vehicle (RV). Systems that level automatically generally include some type of controller that extends and contracts each of a plurality of levelers until at least a portion of the vehicle is level. In most systems there are four levelers or “jacks” typically mounted adjacent the four corners of a vehicle, respectively.
For example, U.S. Pat. No. 5,143,386 issued Sep. 1, 1992 to Uriarte, discloses a motor vehicle leveling assembly including an automatic leveling system that includes a controller that selectively extends and contracts four jacks located adjacent the four comers of a vehicle. The controller includes a proportional tilt sensor that provides output signals corresponding to the degree of tilt of separate axes extending between the jacks. The controller responds to the output signals by energizing the jacks to extend or contract independently at a rate proportional to the tilt along the respective axes. The controller can also energize at least two of the jacks to extend or contract simultaneously to increase the speed of leveling. The Uriarte assembly levels a vehicle by first sensing the degree of vehicle tilt along a pair of diagonal axes that are disposed parallel to lines that extend through diagonally opposite jacks. At least two jacks are then simultaneously and independently expanded in response to outputs from sensors at the lowest corners of the vehicle. The controller expands the jacks at a rate proportional to the degree of tilt in their respective axes as indicated by the output of the tilt sensor.
However, a leveling system constructed according to the Uriarte patent is unable to tailor jack extension rates to respond to vehicle dynamics, cannot measure jack extension without relying on inputs from sensors located in the jacks, and cannot determine vehicle attitude change speed without measuring individual jack extension and contraction. The Uriarte system is also not designed to control tilt rate by changing jack drive rates dynamically and cannot change the jack drive rates based upon inputs other than tilt angle. The Uriarte leveler also cannot automatically select between alternative jack grounding procedures based on vehicle conditions (initial attitude of vehicle) and cannot determine jack ground contact without discrete pressure sensors. Uriarte also did not contemplate automatic selection between alternative leveling algorithms based on vehicle and ground conditions. Neither does the Uriarte system level in pairs parallel to longitudinal pitch and lateral roll (rather than diagonal) vehicle axes. The Uriarte system also lacks a means for maximizing signal stability based on rate of angular change and estimated signal noise. The Uriarte leveling system also does not allow an operator a choice between fully automatic and semi automatic leveling operations and includes no provision to automatically correct long term vehicle attitude changes that occur after initial leveling is complete. Still further, the Uriarte system is only able to accurately adjust the attitude of whatever portion of the vehicle is supporting the tilt sensor—and then only to gravity level.
What is needed is an improved motor vehicle leveling assembly that overcomes the shortcomings of prior art leveling systems.